1. Overexpression of folate binding protein alpha is one of the mechanism explaining the adaptation of HT29 cells to high concentration of methotrexate
- Author
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Charles Adjalla, Renée Hatier, Marie de Nonancourt-Didion, Jean-Louis Guéant, Céline Chéry, and Farès Namour
- Subjects
musculoskeletal diseases ,Cancer Research ,Antimetabolites, Antineoplastic ,Transcription, Genetic ,Enterocyte ,Receptors, Cell Surface ,HT29 Cells ,Folic Acid ,Phosphoinositide Phospholipase C ,Dihydrofolate reductase ,medicine ,Humans ,Protein Isoforms ,heterocyclic compounds ,biology ,Dose-Response Relationship, Drug ,Cell growth ,Binding protein ,Phosphatidylinositol Diacylglycerol-Lyase ,Folate Receptors, GPI-Anchored ,Wild type ,Folate-binding protein ,Molecular biology ,digestive system diseases ,In vitro ,Tetrahydrofolate Dehydrogenase ,medicine.anatomical_structure ,Methotrexate ,Oncology ,Biochemistry ,Drug Resistance, Neoplasm ,Type C Phospholipases ,biology.protein ,Carrier Proteins ,Cell Division ,Protein Binding - Abstract
The human colon adenocarcinoma cell line HT29 can be adapted to 10(-7)- 10(-4) M concentrations of methotrexate (MTX). Cells adapted to 10(-4) M MTX have an enterocyte-like phenotype with DHFR gene amplification. Presently, we hypothetized that an increased expression of folate binding protein (FBP) may participate to the MTX resistance of 10(-4) MTX HT29 cells. The cDNA FBPalpha/beta-actin ratio of amplified transcripts was 4.8- and 1.5- fold higher in 10(-4) and in 10(-7) M MTX HT29 respectively, than in standard type HT29 cells. An increase of transcript level was observed when decreasing folic acid concentration. PI-PLC cleaved 7.7 times more membrane FBP in 10(-4) M than in 10(-7) M MTX and wild type HT29 cells. In contrast to 10(-7) M MTX cells, growth of 10(-4) M MTX cells was dependent on folic acid concentration and abolished at a concentration lower than 0.9 microM. In conclusion, the adaptive mechanism of HT29 cells resistant to 10(-4) M MTX is the result of the synergistic overexpression of both DHFR and FBPalpha. Overexpression of FBPalpha may be related to the enterocyte-like phenotype of the cells.
- Published
- 2001